Hanfeng
Li,
The
State
University
of
New
York,
Buffalo
Entropy
and
L2-torsion”
Given
any
countable
discrete
group
G
and
any
countable
left
module
M
of
the
integral
group
ring
of
G,
one
may
consider
the
natural
action
of
G
on
the
Pontryagin
dual
of
M.
Under
suitable
conditions,
the
entropy
of
this
action
and
the
L2-torsion
of
M
are
defined.
I
will
discuss
the
relation
between
the
entropy
and
the
L2-torsion,
and
indicate
how
this
confirms
the
conjecture
of
Wolfgang
Luck
that
any
nontrivial
amenable
group
admitting
a
finite
classifying
space
has
trivial
L2-torsion.
This
is
joint
work
with
Andreas
Thom.